It could be what you ate.
Or when you ate.
Or how much you ate.
It burns because stomach acids slosh backward into the esophagus.
Common problem foods and drinks are -- Fatty foods, alcohol, carbonated drinks, caffeine,spicy foods, peppermint, chocolate, coffee, tomatoes, and garlic.
What can help --
Eat smaller meals.
Wait at least 2 hours to lie down.
Don’t smoke!
Take an antacid.
If you get heartburn frequently, or if antacids don’t help, call your doctor.